Minimally invasive surgical (MIS) techniques, such laparoscopic, endoscopic, and arthroscopic surgery, are generally performed through small incisions using specialized instruments to accomplish the desired surgical procedure. Usually, the instruments are introduced through a narrow-diameter tube, such as a trocar sleeve, while the physician observes manipulation of the instruments through specialized imaging equipment, such laparoscopes, endoscopes, and arthroscopes. Such MIS techniques offer significant advantages over conventional "open" surgical procedures. In particular, the MIS techniques are usually less traumatic, require a shorter recovery time, and are less costly than corresponding conventional surgical procedures.
Of particular interest to the present invention are laparoscopic cholecystectomy procedures where the gallbladder is surgically severed (commonly referred to as dissected) and withdrawn through a small trocar sleeve, typically having a diameter of about 10 mm. In order to manipulate the gallbladder, several grasping forceps are introduced through additional trocar sheaths, and the position of the gallbladder is constantly changed in order to expose the interface between the gallbladder and surrounding tissue, particularly the liver, to permit dissection. The actual dissection has usually been performed using forceps, hooks, and/or a small gauze pledget to tear and tease the gallbladder from the surrounding tissue along the dissection plane.
While laparoscopic cholecystectomy procedures have been very successful and have become increasingly common, the need to simultaneously handle multiple graspers as well as a dissection instrument places great demands on the physician and usually requires coordination with one or more surgical assistants. The difficulty in performing the procedure is exacerbated by the slickness of the gallbladder surface, and overly vigorous attempts to capture the gallbladder can result in perforation, bile spillage, and gallbladder collapse. A collapsed gallbladder is even more difficult to dissect from the surrounding tissue than an intact gallbladder.
The applications of which this application is a continuation-in-part (the "prior applications") describe a number of retractors for manipulating hollow bodies, in particular, for manipulating the gall bladder in the course of performing a laparoscopic cholecystectomy. The retractors described in the prior applications comprise an elastomeric balloon attached to the distal end of a hollow shaft. With the balloon in a collapsed state, the distal end of the hollow shaft is inserted through an entry hole into the hollow body to be manipulated and the balloon is inflated into an expanded state inside the hollow body. The expanded balloon grips the inside of the hollow body and enables the hollow body to be manipulated as required in the course of a surgical procedure. For example, the retractor can be used to manipulate the gall bladder in the course of a laparoscopic cholecystectomy.
Practical experience has shown that a large manipulation force applied to the hollow shaft causes the elastomeric balloon to distend. Part of the balloon pulls back through the entry hole, resulting in reduced control over the body being manipulated. Distention of the balloon can stretch the balloon to its limit, and cause the balloon to rupture. Moreover, when the balloon is distended, the envelope of the balloon forms a relatively shallow angle relative to the entry hole. The balloon then acts as a lever, stretching, and possibly tearing, the entry hole, which allows the balloon to escape from the hollow body. Finally, when the balloon is distended, it becomes incapable of transmitting a manipulating torque to the hollow body, which reduces the number of manipulating motions available to the surgeon.
The prior applications also show retractors in which the balloon is mounted on the hollow shaft with the balloon attached to the hollow shaft at both ends of a diameter of the balloon. Attaching the balloon to the hollow shaft at both ends of a diameter makes the balloon less prone to distention, and thus to rupturing, and makes the balloon less likely to tear the entry hole. However, with this arrangement, the distal end of the rigid hollow shaft remains deep inside the hollow body while the hollow body is manipulated. Consequently, considerable care must be exercised when manipulating the hollow body using this type of retractor, particularly when applying a manipulating force in the distal direction, to prevent the distal end of the hollow shaft from puncturing or otherwise injuring the hollow body.